Flashover indicator



Sept. 2, 1952 K. R. STEEN 2,609,432

FLASHOVER INDICATOR .Filed July 1o, 195o INVENTOR.

KENNETH R STEEN Biff Patented Sept. 2, 1952 'FLAsHovER INDICATOR KennethIt. Steen, Portland, Orcg., assigner `to the United States of America asrepresented by the Secretary y'of the Interior ApplicationJuly 10, 1950,Serial No. 172,995 y p '72. claims. (o1. 17m-311) (Granted under the actof March 3, 1883, as

The invention described herein may be manufactured and used by or forthe Government of the United States for governmental purposes withoutthe payment to me of any royalty thereon in accordance with theprovisions of the act of March 3, 1883, (22 Stat. 625), as amended bythe act of April 30, 1928, (45 Stat, Li6?, 35 U. S. C., i946 Ed. Sec.45).

This invention is concerned with the protection of electric powertransmission lines. In particular, it is concerned with means forindicating when a tower or pole supporting transmission line conductorshas been subjected to iiashover. It is related to a co-pendingapplication for patent, Serial Number 172,994 iiled by Harold L. Rorden,William E. Scarborough, and Merwin B. Elton.

There are other flashover indicators in the prior art, some of whichresemble the present flashover indicator in some aspects of operation.My invention is concerned with improvements over other similar devices,partly in mechanical structure and partly in method of operation.

This flashover indicator is of the type in which operation isaccomplished with the release of a signaling device by the ignition of asmall charge of explosive powder. The ignition occurs when ahigh-voltage flashover occurs on the line structure to which theindicator is attached.

A principal object of my present invention is the production of aiiashover indicator that is simple and inexpensive, and which willoperate reliably under severe service conditions.

Another object is to produce a iiashover indicator that will operatereliably when infested with vermin such as cocoon-producing larva. Stillanother object is to provide electrical connections for the flashovcrindicator which will provide reliable operation on either steel or Woodtowers of transmission lines.

What `constitutes my present invention is set forth in the followingspecification with reference to the drawing and succinctly defined inthe appended claims.

In the drawing,

Figure 1 is an elevation showing a front view of a preferred embodimentof my invention mounted with appropriate electrical connections on awood transmission line pole.

Figure 2 is a partly sectional elevation of the same indicator as shownin Figure 1.

Figure 3 is a vertical sectional view of the same indicator as shown inFigure 2, showing the indicator in'position prior to operation; takenalong the line 3 3 indicated in Figure 2.

Figure 4 is a horizontal sectional view at the amended April 30, 1928;370 O. G. 757) 2 elevation indicated by the arrows ll-ll'Figure 3.

Figure is an enlarged illustration of the eX- plosive cartridge shown inoperative location in Figures 3 and 4.

In reference to Figure l, a flash indicator case I, made of Bakelite orsimilar material is supported on a wood pole 2 which supportstransmission conductors in the usual way. The iiash indicator case I issupported on pole 2 by an adjustable conducting strap secured by a bolt4 which holds also a bracket 5, a ashover rod 6 and an adjustingdevice 1. Elements 5, 6 and I are adapted from the system of lightninggrounding on which an application for patent, No. 583,483, has beenfiled by Harold L. Rorden.

On pole 2, below the indicator I, there is a loop of wire 8 which isconnected by a Wire 9 to a terminal II on the side of the indicator. Aconnection I2, shown in Figure 3 on the back of case l, connects strap 3to the interior of the indicator.

Hinged at one sidev of case i, near ie bottom, there is an indicatingclosure I4, reierred to as an indicating drop, of the shape ofone-fourth of a circle. On the face I5 of drop I4, a reiiecting surfaceis Provided to make the drop easily seen at night when illuminated by aspot light. The configuration of drop I4 is such that when the indicatoris set prior to an indication, the bottom of case I is closed by thebottom of indicator I4. The drop is shown open in Figure 1.

A wire spring I6 is provided inside the indicator to provide amechanical force on drop I4 tending to force the drop open.

The drop, under normal conditions, is held in the closed position by anexplosive link 22 made of a glass tube containing a charge of powder 23between the ends of two connecting electrodes 24 and 25. The link 22 isplaced in position as shown in Figure 3 in which end 25 of the linkrests in a hollow conducting rivet 26 in the back of case I. Rivet 26 ismetallically connected to a strip I2 arranged to be in contact withstrap 3 when mounted on pole 2.

The front end 24 of cartridge 22 is supported in a hollow conductingrivet 21 connected to Iterminal II. A hole 28 in the face I5 of dropIll, coaxial with the centers of rivets 26 and 2l er1- gages the body ofcartridge 22 when cartridge 22 is in place as shown in Figure 3.Cartridge 22 is placed in position by lifting closure I4 into the closedposition shown in Figures 2, 3, and 4 and inserting cartridge 22 throughhollow rivet 22 and through hole 28 so the end 25 rests in rivet 26.

Cartridge 22 then, in bending moment, resists the force of spring I6holding closure I4 in position against the opening force.

When a ashover occurs on pole 2, a potential difference isset up.between strapS and wire' 8 sufcient to'flash over in cartridge 22between electrodes 24 and 25 exploding powder charge 23.

provided to hold drop I4 up in the closed position rIhe tube ofcartridge 22 is shattered by the explosion of powder 23 so thesupportformerly from when released, coaxial openings in said case nolonger exists. Drop I4 then is opened-by the 1 Fig. 1.

In reference to the co-pending applicationfor.

patent referred to above, the electrical principles of operation thereinare identical with 'those in my invention. Cartridge 22 is substantiallythe same for both devices. The differencefbetween these two inventionsis that whereas in the earlier one cartridge -22 was held by metallicclips .which placed cartridge 22 in cantilever. stress; my in ventionlsupports the load of closure `I4 in the middle of cartridge 22 betweenthetwoends 24 and 25 which are both supportedy .against the bendingload; A .This tends to prevent mechanical creepage of electrodes 24 and25 in cartridge 22 and to prevent accidental breakage. It is easier inmy invention to insert cartridge 22 when setting the device'. All thatis required in myinvention is to lift closure I4 to the closed positionand insert vcartridge 22 with a single movement through rivet 21 andhole 28,and into rivet 25. The delicacy of adjusting a metal clip and ametal catch as required in the earlier device'is avoided.

The mechanical arrangement shown in the drawings is one found byexperience to be practical and economical. This arrangement, however, issubject to considerable variation. It is obvious; forV example, thatthehole 28 in drop I4 could be eliminated and that the same result could beaccomplished by a projection at the edge of the face I arranged toengage cartridge 22.

and in said drop and an explosive shatterable c c U cartridge insaidcoaxial openings in said case force of spring I6 into thev positionL'showricin' l l and drop, said` cartridge being placed in said openingsin double shear to hold said drop normally inclosed position.

2. Ina ilashover indicator the combination of an insulating case, ahinged indicating drop nor- -mallyf held in said case against the forceof a spring Vin said case, coaxial openings in said case REFERENCESCITED The following references are of record in the ille of this patent:

c UNITEn STATES PATENTS Number Name Date 2,006,179 Price, et al June 25,1935 2,018,459 Menger Oct. 22,- 1935 2,138,430 Rudd Nov. 29, 1938 IFOREIGN PATENTS Number Country Date l l888,842 France Sept. 20, 194 3

